1. Field of the Invention
The present invention relates to the manufacturing of roofing shingles.
2. Description of the Prior Art
A laminated roofing shingle design has recently been developed. The laminated shingle includes a two layer shingle in which a narrow strip of asphalt saturated felt is attached to the exposed edge of the shingle to give the roof of a dwelling an improved appearance by presenting to the viewer's eye a thicker shingle edge.
U.S. Pat. No. 3,998,685 (Czyzewski, et al.) discloses an apparatus and process for making an offset laminated roofing shingle of the type described above. This patent discloses an apparatus for saturating and longitudinally cutting a continuous felt strip into first and second sheets and then laterally shifting the narrower shim sheet into a position below the remaining wider overlying sheet. After the felt sheet has been cut into the first and second sheets and after the narrower sheet has been shifted into alignment with the center line of the wider sheet, both the narrow and wide sheets are no longer aligned with the center line of the processing machinery.
Since all existing roofing shingle manufacturing machinery produces various products one at a time and since non-laminated roofing shingles are maintained on the machinery center line during the entire manufacturing process, the roofing shingle manufacturing machinery must be shut down and certain elements of the machine must be repositioned to manufacture laminated shingles which beyond a certain point do not travel along the center line of the machinery. Making the necessary machinery modifications takes time and results in lost production.